<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006-2012 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------
// $Id: CacheSqlite.class.php 2734 2012-02-14 06:55:15Z liu21st $


/**
 +--------------------------------
 * Sqlite缓存类
 +--------------------------------
 */
class CacheSqlite extends Cache {
	
	/**
     +----------------------------------------------------------
	 * 架构函数
     +----------------------------------------------------------
	 * @access public
     +----------------------------------------------------------
	 */
	public function __construct($options = '') {
		if (! extension_loaded ( 'sqlite' )) {
			throw_exception ( L ( '_NOT_SUPPERT_' ) . ':sqlite' );
		}
		if (empty ( $options )) {
			$options = array ('db' => ':memory:', 'table' => 'sharedmemory', 'expire' => C ( 'DATA_CACHE_TIME' ), 'persistent' => false, 'length' => 0 );
		}
		$this->options = $options;
		$func = $this->options ['persistent'] ? 'sqlite_popen' : 'sqlite_open';
		$this->handler = $func ( $this->options ['db'] );
		$this->connected = is_resource ( $this->handler );
	}
	
	/**
     +----------------------------------------------------------
	 * 是否连接
     +----------------------------------------------------------
	 * @access private
     +----------------------------------------------------------
	 * @return boolen
     +----------------------------------------------------------
	 */
	private function isConnected() {
		return $this->connected;
	}
	
	/**
     +----------------------------------------------------------
	 * 读取缓存
     +----------------------------------------------------------
	 * @access public
     +----------------------------------------------------------
	 * @param string $name 缓存变量名
     +----------------------------------------------------------
	 * @return mixed
     +----------------------------------------------------------
	 */
	public function get($name) {
		N ( 'cache_read', 1 );
		$name = sqlite_escape_string ( $name );
		$sql = 'SELECT value FROM ' . $this->options ['table'] . ' WHERE var=\'' . $name . '\' AND (expire=0 OR expire >' . time () . ') LIMIT 1';
		$result = sqlite_query ( $this->handler, $sql );
		if (sqlite_num_rows ( $result )) {
			$content = sqlite_fetch_single ( $result );
			if (C ( 'DATA_CACHE_COMPRESS' ) && function_exists ( 'gzcompress' )) {
				//启用数据压缩
				$content = gzuncompress ( $content );
			}
			return unserialize ( $content );
		}
		return false;
	}
	
	/**
     +----------------------------------------------------------
	 * 写入缓存
     +----------------------------------------------------------
	 * @access public
     +----------------------------------------------------------
	 * @param string $name 缓存变量名
	 * @param mixed $value  存储数据
	 * @param integer $expire  有效时间（秒）
     +----------------------------------------------------------
	 * @return boolen
     +----------------------------------------------------------
	 */
	public function set($name, $value, $expire = null) {
		N ( 'cache_write', 1 );
		$expire = ! empty ( $expireTime ) ? $expireTime : C ( 'DATA_CACHE_TIME' );
		$name = sqlite_escape_string ( $name );
		$value = sqlite_escape_string ( serialize ( $value ) );
		if (is_null ( $expire )) {
			$expire = $this->options ['expire'];
		}
		$expire = ($expire == 0) ? 0 : (time () + $expire); //缓存有效期为0表示永久缓存
		if (C ( 'DATA_CACHE_COMPRESS' ) && function_exists ( 'gzcompress' )) {
			//数据压缩
			$value = gzcompress ( $value, 3 );
		}
		$sql = 'REPLACE INTO ' . $this->options ['table'] . ' (var, value,expire) VALUES (\'' . $name . '\', \'' . $value . '\', \'' . $expire . '\')';
		if (sqlite_query ( $this->handler, $sql )) {
			if ($this->options ['length'] > 0) {
				// 记录缓存队列
				$this->queue ( $name );
			}
			return true;
		}
		return false;
	}
	
	/**
     +----------------------------------------------------------
	 * 删除缓存
     +----------------------------------------------------------
	 * @access public
     +----------------------------------------------------------
	 * @param string $name 缓存变量名
     +----------------------------------------------------------
	 * @return boolen
     +----------------------------------------------------------
	 */
	public function rm($name) {
		$name = sqlite_escape_string ( $name );
		$sql = 'DELETE FROM ' . $this->options ['table'] . ' WHERE var=\'' . $name . '\'';
		sqlite_query ( $this->handler, $sql );
		return true;
	}
	
	/**
     +----------------------------------------------------------
	 * 清除缓存
     +----------------------------------------------------------
	 * @access public
     +----------------------------------------------------------
	 * @return boolen
     +----------------------------------------------------------
	 */
	public function clear() {
		$sql = 'DELETE FROM ' . $this->options ['table'];
		sqlite_query ( $this->handler, $sql );
		return;
	}
}